1. Field of the Invention
The present invention relates to an image pickup device of an electronic still camera (also called a still video camera) or the like using a solid state image pickup element such as a CCD, and more particularly to a noise suppression technique.
2. Related Background Art
In order to suppress noises of an image pickup device of an electronic still camera, a method is known whereby an image signal outputted from the image pickup device is subtracted by a signal obtained when the image pickup device is light-shielded, to thereby reduce fixed pattern noises in each frame.
Such a method can suppress fixed pattern noises, but random noises are multiplied by 1.4 or a root 2. Furthermore, noises are extracted in a manner similar to the image taking operation, near at the time before or after an image is taken, resulting in a poor operation speed of continuous image taking of a camera.
The present invention has been made under such circumstances. It is an object of the present invention to provide an image pickup device capable of reducing fixed pattern noises without increasing random noises.
Apart from the above, in order to deal with a defective pixel of a CCD, data of a pixel one pixel before the defective pixel has been conventionally replaced with that of the defective pixel.
Such a conventional method allows a replacement of a preceding signal with a succeeding signal because of the order of reading pixels of a CCD. However, it is difficult to replace a succeeding signal with a preceding signal. Some images have a strong correlation in the vertical direction. In such a case, it is preferable to replace the signal of a defective pixel with that of a pixel at the upper or lower row. However, a conventional method is not suitable for such correction.